An IC (Integrated Circuit) card has been used for not only a credit card, a commutation ticket, account settlement of other business transactions but also used in various fields as an ID card, e.g., an employee ID card, a membership card, or a health insurance card. That is because the IC card includes an IC having a CPU, an ROM, an RAM, an EEPROM, and others to realize various functions as compared with a conventional magnetic card and counterfeiting the IC card is difficult, which greatly improves security.
ISO/IEC 7816-1 part 1, 2 discloses a structure of an IC card. For example, the IC card stores important information such as personal information. To assure security, the important information stored in the IC card is encrypted, and authentication with respect to an IC card user is requested.
However, a CPU may erroneously operate in some cases when noise is applied to a power or a clock supplied to the IC card or light is applied to an IC chip itself, and a countermeasure against a fraudulent transaction that intentionally provokes such an erroneous operation is desired. To realize this, a measure of mounting a filter that eliminates an influence of noise on an LSI itself is taken. However, this measure alone cannot sufficiently avoid an erroneous operation of the CPU.
Further, JP-A 2005-285133 (KOKAI) discloses a technology of detecting an erroneous operation to appropriately continue or stop processing in accordance with a type of the erroneous operation.